Supercharger for internalcombustion engines



Aug. 21, 1951 B. SCOTT SUPERCHARGER FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 29, 1949 girl/I1 INVENTOR. BUGHER SCOTT BY flu 7 ATTORNEY Patented Aug. 21, 1951 UNITED STATES PATENT OFFICE SUPERCHARGER FOR INTERNAL- COMBUSTION ENGINES Bucher Scott, Atlanta, Ga.

Application September 29, 1949, Serial No. 118,557

3 Claims. 1

This invention relates to a supercharger for internal combustion engines and more particularly to an improvement in the fuel injection system of internal combustion engines of the two cycle type in which the fuel is pulled into the cylinders through reed valves on a hollow crankshaft main bearing.

In one type of well known two cycle engine the carburetor is located immediately below the crankcase and injects the mixed fuel into a cylindrical hollow crankshaft bearing which has ports in each flat face controlled by reed type valves. The upward compression stroke of the piston creates a reduced pressure in the crankcase to open the corresponding reed valve, thereby withdrawing the fuel from the carburetor; and the downstroke or power stroke compresses the fuel in the crankcase as the piston moves down, first passing the exhaust opening permitting the burned fuel to escape and then passing the intake opening permitting the newly compressed fuel to rush into the cylinder. Where there are two cylinders, the two reed valves are alternately opened and closed by the action of their respective pistons.

The two cycle engine depends for maximum performance upon getting a large amount of the fuel mixture into the crankcase and from there into the respective cylinders. However, in the prior construction of these engines, top performance is not obtained due to the failure of the pistons in completely withdrawing and efficiently agitating the fuel mixture from their respective reed valves.

It is an object of this invention to improve the fuel injection system of certain types of two cycle engines.

Another object of this invention is to provide supercharging elements on the faces of the crankdiscs of two cycle engines which derive their fuel mixture from a combined crankshaft main bearing and valve housing provided with reed valves.

A further object of this invention is to provide supercharging elements which may be easily and economically applied to two cycle engines presently in use.

Also an object of this invention is to increase the turbulence of the fuel mixture after it is pulled from the reed valves on the hollow crankshaft main bearing.

Other and further objects and advantages of my invention will be apparent from the following description taken in conjunction with the accompanying drawings in which like characters of i ends by journals l8 and IS.

reference designate corresponding parts throughout the several views and wherein: I

Fig. l is a side elevation of a conventional two cycle engine with parts broken away and with my invention mounted on a part thereof.

Fig. 2 is a cross-sectional View taken on the line 2-2 of Fig. 1.

Fig. 3 is a cross-sectional view taken on the line 8-3 of Fig. 2.

Fig. 4 is a cross-sectional view similar to Fig. 2 showing a modified form of my invention.

Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 4.

Fig. 6 is a cross-sectional view similar to Fig. 2 showing a modified form of my invention.

Fig. 7 is a cross-sectional view taken on the line ll of Fig. 6.

A conventional two-cycle engine designated generally at It comprises a cylinder block I i having cylinder walls l2 and a crankcase I3. A magneto ignition system M selectively fires spark plugs l5 and !5'. Inside the crankcase I3 is a crankshaft it supported at the center on a hollow crankshaft center main bearing l l and near the Crankshaft I6 is provided with two aligned pairs of eccentric crankdiscs 2i), 2!! and 2i, 2!, the pair 26, 28' being arranged to counterbalance piston rod 22 and its associated moving parts, and the pair 2i, 2i being arranged to counterbalance piston rod 23 and its associated moving parts. Piston rods 22 and 23 are operatively connected to pistons 24 and 25, respectively, which are mounted for reciprocating movement inside cylinder walls i2.

The fuel injection system of the engine ll! comprises a carburetor 26 mounted immediately below the crankshaft bearing ll on the crankcase l3. A T-shaped passage 2"! leads through the crankcase 13 into the crankshaft main bearing I! and terminates in valve ports on opposite faces of the bearing [1. Reed valves 28, 28', fixed at one end, operably control the valve ports on the respective faces of crankshaft main bearing ii.

In the operation of the fuel injection system, the fuel which is mixed in the carburetor 2 5 is pulled through the T-shaped passage Zl and selectively Withdrawn from the reed valve ports adjacent the reed valves 28, 28 by the suction of the pistons 24, 25 during their respective upward compression strokes. Since the carburetor is open to the T-shaped passage 2? at all times, the amount of fuel withdrawn from each valve port during each open position of the respective reed valves 28, 23' depends upon the reduced pressure created in the crankcase It in the vicinity of the valve ports.

My invention, as best seen in Fig. 2, comprises equally spaced protruding turbine like curved supercharging blades 29, 29 fixed to the inside faces adjacent the upper edges of the crankdiscs 20 and 2|, respectively, and being slightly offset from their respective radii on crankshaft it. The blades 29 on crankdisc 20 are adjacent the reed valve 28 on the bearing ll, while the blades 29' on the crankdisc 2| are adjacent the reed valve 28.

In the modification illustrated in Fig. 3, open protruding cups 30 replace the blades 29 on the crankdisc 29 and may be used in the same relationship on disc 2| in the embodiment of Fig. 1.

In the alternative form of construction of Fig. 6,- cup shaped indentations 3| are formed adjacent the upper marginal edge on both faces of the crankdisc 2B and on the upper peripheral surface, replacing the blades 29 of Fig. 2 or the cups 39 of Fig. 4. It is obvious that many different types of indentations, grooves or slots may be used on the crankdiscs to produce the supercharging effect.

Increased power and turbulence may be produced in the crankcase It by placing either the protruding blades 29, the cups 3%, or the indentations 3| on both the inside and outside faces of the crankdiscs 2E and 2|; and, further, may be placed on the faces of the crankdiscs 2i) and 2%. The addition of the supercharging members to all crankdisc surfaces is desirable but a substan-- tial increase in performance is receive by only placing the supercharging elements on the faces of the crankdiscs adjacent the reed valves 23 and 28'.

The operation of my invention becomes apparent as the flow of the fuel mixture is followed through from the initial carburation to the point of combustion. The fuel mixture leaves the carburetor 26 passing into the T-shaped passage 2?. Assuming that piston 25 has just begun the compression stroke, the reed valve 28 is pulled open by the pressure reducing action of the piston 25, and the disc 2| rotates about the center of the crankshaft I 6 carrying either the blades 29, the cups 30, or the indentations 3| according to which form of construction is preferred, producing a circular turbulent motion adjacent the reed valve 28. This action of the blades 29, or the modified forms, in the vicinity of the port on bearing I"! near reed valve 28' creates an additional suction on the open port and withdraws a maximum amount of fuel mixture for that particular cycle. During the short interval after the mixture is withdrawn and the reed valve 28' has closed, the blades 29 continue to agitate the fuel mixture, creating a turbulence and assisting the mixture to move up through the intake 4 opening into the upper cylinder portion for the compression and combustion. Upon the completion of the stroke of piston 25, the piston 25. and consequently the blades 29 on disc 2!! function for that cylinder in the same manner as the piston 25 and the blades 29 on disc 2|.

The effect of my new and useful improvement eliminates lost efficiency in the vicinity of the valve ports by withdrawing a maximum amount of fuel mixture from the carburetor and assures a thorough mixture up to the very point of combustion. The modification of Figs. 4 and 6 function in the same manner as that of Fig. 2 with the cups 30 or the indentations 3| being an alternative form of construction for certain load and torque characteristics.

It will be obvious to those skilled in the art that many modifications and changes may be made in the embodiment shown and described without departing from the scope of my invention as defined in the appended claims.

I claim:

1. In an internal combustion engine in which fuel is introduced through a crankshaft bearing having a reed type valve adjacent a crankdisc, indentations on said crankdisc arranged to assist the passage of fuel through said reed valve to increase the output and efficiency of said engine.

2. In an internal combustion engine in which fuel is introduced through a crankshaft bearing having a reed type valve adjacent a crankdisc, cup shaped indentations on said crankdisc faces adjacent said reed valve arranged to assist the passage of fuel through said reed valve to increase the output and efficiency of said engine.

3. In an internal combustion engine in which fuel is introduced through a crankshaft bearing having reed type valves adjacent to crankdiscs, indentations on both faces and the peripheral surface of said crankdiscs arranged to assist the passage of fuel through said reed valves to increase the output and efficiency of said engine.

BUCI-IER SCOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 963,365 Gathmann July 5, 1910 1,213,519 McLaren Jan. 23, 1917 1,451,407 Sargent Apr. 10, 1923 2,124,196 Kottsieper July 19, 1938 2,442,217 Smith May 25, 1948 FOREIGN PATENTS Number Country Date 104,091 Great Britain of 1917 

